First opened Tuesday, June 11, 2013
お兄さん
おにいさん
Pitch accent: We don't have the data for this section. No accent list gives this spelling and reading, or the two we check against disagree.
(someone else's) older brother (formal)
Taken apart
We don't have the data for this section. Wiktionary has no Etymology section for this reading, and a split made without one would be a guess.
Written with 兄
In a sentence
君はお兄さんにそっくりだよ。
You look just like your big brother.
彼は彼のお兄さんに劣らず賢い。
He is no less wise than his brother is.
Sentences are from Tatoeba (CC BY 2.0 FR), picked by fixed rules from a dated export and shown unchanged. Nobody has reviewed them one by one.
What Wiktionary says
We don't have the data for this section. The pinned Wiktionary dump has no Etymology section for this reading, so nothing is said about where the word comes from.